Good Stone? Why GIA Cert and Sarin Rpt Different?

[marlowe]

Hi I just bought this stone today but after I got home I noticed some differences in the Sarin and GIA reports. Please take a look. I’d love to hear what people have to say about this…

From GIA Sarin

Shape: ROUND-P8-P8

Est Weight: 1.316cts
Diameter: (7.03mm-7.06mm) 7.05
Crown: 34.69 34.5
Pavilion: 40.51 40.6
Star Length: 55.9% 55%
Girdle Th: 3.47% 3.5%
Culet Size: 0.6%
Est GIA Cut: Excellent
Table: 56.0% 56%
Crown Height: 15.16% 15.0%
Pavilion Depth: 42.49% 42.5%
Lower Halves: 76.1% 75%
Required Girdle Min/Max: THN-STK
T. Depth: 61.12% 61.1%
Min Required Finish: Very Good
From GIA Cert:
SI1
G
Cut Grade: Excellent
Polish: Excellent
Symmetry: Excellent
Fluorescence: None.
HOWEVER, GIA CERT LIST SLIGHTLY DIFFERENT MEASURENTS FOR THE FOLLOWING (Measurements not listed here are the same as on Sarin report):
T. Depth: 61.4
Crown: 35.0
Crown Height: 15.5%
Pavilion Depth: 43%
Culet: None
1) Why the differences in the Sarin report done today and the GIA cert dated 5/18/07? Can these variances be chalked up to a Sarin machine that hasn’t been calibrated in a while? Is the cert for a different stone (albeit one very similar)?
2) I paid $8,600. Was that a good price?
3) On the Sarin report why are there two numbers for everything? Is one the high and one the low for the angles and degrees?
Thanks for you comments. I’d really appreciate getting feedback. Can’t tell if I should be alarmed or not.

 

[WorkingHardforSmallRewards]

First of all, very well put together.

secondly, I had a similar problem with 2 sarin reports showing different numbers and those form the AGS report. I have talked to a number of people for a variety of reasons and each time a Sarin analysis is done you will find there is some difference, however yours shows nothing alarming. You can do a search and you will find a tremendous amount of information on this.

Thirdly, I am too tired to run a search at the moment, but head to the top of the pricescope home page and enter your data, that will bring up similar stones and allow you to compare prices with those available here.

finally, I am not sure but I think that the second number listed is rounded to represent the rounding done by GIA and thus give GIA equivalent numbers for easier understanding and translating. Also, GIA will undoubtedly have nicer equipment, thus yielding a more accurate result. The best way you are going to be able to identify the diamond is going to be based on inclusion plots, but at the moment there are no red flags shown from one to the other, which might be a bit presumptuous of me to say without more experience but I certainly don't see anything that looks like a major deviation.

I mean, when you think about it you are within .5 or .6% at max deviation and 1% of a 7mm diamond would be .07mm, so that means at max the deviation is .035mm. Now .035 mm difference seems to me pretty reasonable for a slightly lesser quality machine not being perfectly calibrated, etc...

 

[marlowe]

WorkingHardforSmallRewards,

Like your name. Thanks for your response. Your comments about your experiences with two different Sarin reports for the same stone yielding slightly different results gives me great confidence and comfort.

 

[WorkingHardforSmallRewards]

well to expand a little more. I had James Allen run a report that was at no point more than .2% off of the AGS report in angles. though there was one somewhat odd ball crown height thrown in. I tihnk that was because it had actually measured the width slightly less than it actually is. In those regards run a search again, and you will find that for a long time there was an issue with Sarin's coming back with incorrect measurements and I recall strmdr (if you recognize that name) commenting on how the Sarin should not be relied on for the actual measurements, GIA and AGS will be much more accurate in that regard. Nontheless, the angles and all other numbers were within .2%

Then I got my diamond. and it had stickered to it a second Sarin Analysis which was like your with a .6% culet and the girdle said slthk-slthk, when in fact it is thin-slthk. That report was run in Israel at the actual cutting location.

So bassically, the machine in Israel reported the diamond as ideal but somewhat off of the ideal figures I was really looking for.

Then the Sarin by James Allen was very much ideal and as far as any reasonable expectations are concerned it was virtually the same as the AGS report.

Then the AGS report had what should be considered the closest to true numbers.

but again, they also have a margin of error and per my own research and to again bring up strmdrs comments, the truth is probably somewhere between the JA and AGS numbers(and the Israeli analysis, as it was very very similar in other dimensions)

Again, run a search and you will find a plethora of information from concerned consumers like ourselves.

Also, I decided to primarily aim for AGS certs a while back (though its not something I would necessarily recommend), but during my research of the GIA cut I recall finding a lot of information on the GIA rounding process. This information is available on the GIA website and also on price scope if you run some searches. So my thoughts are that GIA will have some margin of error and then round slightly, and then this analysis has some margin of error (hence the rounded numbers made available) and by placing more faith in the GIA numbers but recognizing they too will be slightly (but inconsequentially) off then it is quite reasonable to have the reality of the diamond somewhere between the two reports but slightly in favor of GIA (and again, that would amount to .008-.012mm error in the GIA analysis per my rough assumption driven calculations. Which being anywhere near the truth is REALLY pretty small.) They are all quite close. I haven't actually analyzed the numbers, just looked at the differences, but you can plug it into the HCA and take a quick check on how it is likely to perform. and since I am still awake I guess I will take a closer look at them.

 

[WorkingHardforSmallRewards]

Well I didn't bother plugging it into the HCA because I am positive it will return a great score and its always more fun to do yourself. But just to ease your mind. The research I have done shows that the 43% pavilion depth is very desirable within .5 plus or minus range, so nothing to worry about there. Everything else is checking out quite well and that can be confirmed yourself with plugging in both Sarin and GIA numbers into the HCA.

So even on the Sarin everything is checking out ok.Stars, LGF, girdle, depth, table, angles, all is great in both Sarin analysis and GIA report with very minimal variation. If anything this should be a confidence builder.

Edit: to use the HCA go to the top of this page and locate the "tools" link, from there you can plug in the numbers in the "cut adviser"

 

[marlowe]

WorkingHardforSmallRewards,

Yep. I’m still up too. But not for long. I ran a HCA using both the Sarin and GIA figures and got like 0.7 and 0.8. (I was actually surprised that there was so little variance in the HCA results. I have seen grater differences in HCA results with far fewer differences in %s.) Anyway, the diamond looked very good under an ideal-scope. (Hard for me to tell difference between great and very good w/ideal-scope.) It looked great using the H&A scope for symmetry. So I am happy with the purchase.

I really appreciate your comments about the differences in measurements using different labs/equipment. I had, prior to your comments, thought of a Sarin report as de facto. I am in finance so I tend to rely on numbers. However, I’m learning that all that really matters with a diamond is how it looks (in natural sun light, office light, and of course, candle light).

Thanks again,

 

[WorkingHardforSmallRewards]

yea, thats not bad, its almost getting into that too good range

However, I had been looking at the 40.6% pavilion angle but I am not too sure about the 40.5% but then again, its probably not accurate enough and I bet its right at 40.7. And if the IS image is excellent, no worries! well done! post up pictures, IS image, whatever, its always fun to observe while I am trying to learn new stuff at 5am on the weekend

and now: